Air dry



Oct. 23, 1945. w. 0 HEDGES ETAL 2,387,395

PATENT LEATHER Filed Jan. 19, 1940 Fig.1

PRSTE-UKE 0MB COMM APPUED 0N FLEXlBLE BRSF. MATERlAL AIR DRYJDR FORCE MR DRY COAUNG AT I85'T0 ZGO'F.

APPLY MMTMRL CORUNH COMPRlSING THWNED DAUB COMPOSVHON MR DRY,0R FORCE RIR DRY COATINGS M \85' TO 2.00 E

APPLY A CLERR, FLEMBLF. VARNDH 0R LHEQUER CORUNG DRY LOATED PRODUCT FOR SEVERAL HOURS, 09. OVERNKHT N \15' M851:

lnvtmoa:

Tmvuum Dnuutons Nmmfl C. Haunts J on u C. Lon A N DnuBLonT 1mm Kean ATTORNEJGS Patented Oct. 23, 194

PATENT LEATHER William D. Hedges, John'C. Lowman, and Thomas J. Kerr, Columbus, Ohio, assignors to Columbus Coated Fabrics Corporation, Columbus, Ohio, a

corporation of Ohio Application January 19, 1940, Serial No. 314,684

2 Claims.

This invention relates to an improved composition and process of making patent leather or similar enameled fabric base material having a high glossy surface.

It has been observed in the manufacture oi patent leather that the enamel and varnish coatlngs applied over pyroxylin base compositions plasticized with the usual substances, such as castor oil, dibutyl phthalate, tricresyl phosphate, and the like, do not dry satisfactorily. This is due to the exudation oi the plasticizer, or softening agent. from the undercoating and into the superimposed coating at the temperatures required to dry the enamel or varnish composition. These plasticizers act as oxidation inhibitors and retard the dry g of the enamel or varnish coating to such an xtent that it is impossible to produce a dry, tack free, hard film by the usual method of baking or drying the coating films. This follows even when rapid drying coating composition is used, such as the oleoresinous varnishes nfide with alkyd resins.

It is an object of this invention to overcome these difiiculties and to produce an improved patent leather finish having a highly flexible, tack tree, durable finish which retains its fiexibility upon aging.

Another object is to produce an improved patent leatheanmaterial which will withstand repeated fie g and bending without cracking, chipping, or peeling.

Another object is to provide an improved plasticized undercoating adapted for application to a flexible base material which will not exude the plastlclzer at the temperature of baking the superimposed enamel and varnish coatings.

These and other objects will appear in the following description and drawing, which forms a part of this specification.

In the drawing:

Figure 1 illustrates diagrammatically the steps involved in making the patent leather finish of this invention;

Figure 2 an enlarged fragmentary cross sectional vi owing the built-up coated fabric patent leather material made in accordance wit this invention.

In the manuiacture oi patent leather and equivalent enameled fabric, as shown in Figures 1 and I coat a of more liquid consistency. To this end the portion 0! the daub coating composition is thinned by introducing quantities of a s vent.

Over the coating b is applied a clear xible varnish or lacquer coating c which is dried at about 1'75 to 185 degrees F. to produce a high gloss surface finish. This coating may be applied by spraying, brushing, or flowing. It will be understood that the initial base coating will be of such consistency whe applied that it will not flow through the interstices between the fibers forming the flexible base support.

For compounding the base coating for making patent leather, the pyroxylin composition is employed, together witlna plasticizer, pigment, and solvent and applied in the form of a viscous or paste-like consistency. The plastlcizer used in formulating the pyroxylin base coating is a resinous modified castor oil reacted product which does not exude from the coating when the same is subjected to temperatures around 185 degrees 1''. This composition comprises a resin -like plasticizer and is made by reacting castor oil with maleic anhydride and glycol.

The iollowinfi illustrate typical examples 0Q the method of making the plasticizer or softener utilized in making the cvted products of this invention:

Example I A mixture 01' 150 parts by weight of castor oil, 31 parts by weight of glycol andparts by weight of maleic anhydride is heated together in a reaction chamber, with or without stirring or blowing with 00:, at a temperature oi app oximately 230 degrees C. for 12 hours. The reaction chamber is preferably euipped with a stirrer, and provision is made for escape or the water formed 2, leather, cloth, or other suitable flexible base 50 during the reaction, while at the same time loss of glycol is prevented. when the product is heat treated for this length of time the product is in the form of a gel. If it is desired to carry the resin to this state it is preferable to add a solvent such as toluol or xylol thereto while the r is still hot. This prevents the resin from going into an insoluble state before it is used, and also provides a product which is readily dispersed in coating compositions. It CO: is used the alcohol compatibility of the resin is somewhat decreased and the cooking time is shortened. Carbon dioxide may be introduced by bubbling the gas through the mixture. With the use of carbon dioxide a lower acid value resin is produced.

Example II In this example, 400 parts by weight of castor oil. 26 parts by weight of diethylene glycol and 50 parts by weight of maleic anhydride are mixed together and heated as described under Ex; ample I. Using the same temperature in cooking, the time is reduced from 12 to 8 hours. The acid number and alcohol solubility of the final resinous product are affected by the some factors as are'noted under Example I. In this case the final product has an acid number of about 9 without the use of CO2. By heat treating the resin for longer than 8 hours at a temperature between 200 and 250 degrees C. the final resinous product will be in the form of a diillcultly soluble gel.

Example III In this example, 800 parts by weight of castdr oil, 50 parts by weight of maleic anhydride and 26marts by weight of glycol, preferably diethylene glycol, are mixed together and heated, as set out above in Example I. In this instance the cooking time is about 14 hours at 230 degrees C. The resinous product produced has an acid number of about 9. A longer cooking time will produce a substantially insolu resin. Where the resin is to be cooked to pr duce a product having a high viscosity it is preferable to add toluol or xylol in sufllcient amount while the resin is hot so as to prevent the product from going over into an insoluble state u on cooling. The resins made and described wil continue to polymerize at temperatures below 200 degrees C. and even below 100 degrees C. so that the introduction of solvent to prevent the polymerization from continuing so as to produce an insoluble solid gel is required.

In this instance 1000 to 1200 parts by weight of castor oil are mixed with 26 parts by weight of diethylene glycol and 50 arts by weight of maleic anhydride and the mixture heat treated as in the previousixample. The time required for cooking this batch is much longer than that for the previous example. It was found impossible to produce a gel from this combination even after cooking the resinous batch for 27 hours at 275 degrees C. The product, however, results in yielding a bodied oily resin having definite advantages as a plasticizer over raw castor oil.

It will be understood that in the above examples other equivalent ingredients may be used in compounding the plasticizer. Any oil comprising hydroxyl groups in its formula, which is capable of becoming dehydrated and which after @uch dehydration is converted into a drying oil.

Example IV assasos may be substituted for castor 011. Further, suitable portions of castor oil may be replaced with any one or more of the non-drying or semi-drying oils. Glycols having the general formula CnH2n(OH)2 may be used in making the resin. diethyiene glycol being preferable. Triethylene, propylene and higher glycols may be used in place of ethylene and diethylene glycol. Some glycols offer definite advantages over others, in certain cases, as for example when diethylene glycol is substituted for ethylene glycol, the cooking time of the resin is decreased. This invention, however, is applicable to the use of various polyhydric alcohols including glycerin which react similarly as the glycols to produce th P ticizing resin.

In the examples maleic anhydride is the polybasic acid preferably used, but other polybasic and monobasic unsaturated acids such as fumaric, acrylic, crotonic and the like may be utilized in place of maleic. In general, all unsaturated polybasic carboxyiic acids of the aromatic, aliphatic or heterocyclic may be employed. The higher viscosity plasticizlng compositions show less tendency to exude than the lower viscosity less polymerized plasticizer product. The pins. ticizer formulated using 800 parts of castor oil, as shown in Example 111, has a viscosity of approximately 450 centipoises. In the formulation using 1000 parts of castor oil, as given in Example IV, the viscosity of the final product is about 60 centipoises.

In the manufacture of patent leather-like products of this invention, one or more coatings is applied to a suitable cloth, fabric, or felted base material and each of the coatings is plastlclzed with the maleic-anhydride-glycol modifled castor oil product of which Examples I to IV are illustrative. Due to the higher exudation temperature of the modified castor oil plasticizer relatively long oil drying varnishes can be applied and dried over this undercoating. Further, it has been found that when certain pigments, such as Milori Blue (ferric-ferro-cipnide), asbestine, and like substances are used in combination with the maleic-anhydride-glycol modified castor oil plasticizer in the pyroxylin undercoatings long oil varnishes dried over the pyroxylin base material as readily as they would over an oil base coating. With the use of bone black, lampblack, carbon black, and thopone, the coating varnish dried more slowly, hich it is believed was due to the catalytic action of the pigment. Exudatlon of the plasticizer was prevented due to the formation of a gel-like structure of the plasticizer.

Typical examples of formulations used in compounding the base and thinned undercoatings are as follows:

Example V Parts by weight Nitrocellulose (30-40 sec. viscosity) l0 Plasticizer (Example III) 15 Plasticizer (Example IV) 10 Asbestine 35 Pigment (bone black) "5. 6 Solvent 20-30 The solvent used is that conventionally used for dissolving pyroxylin and preferably comprises a mixture by volume of 40 per cent ethyl acetate. 35 per cent alcohol, and 25 per cent toluol. Other suitable solvent mixtures for dissolving the nitrocellulose may be used.

Another example of an undercoating base is as follows:

Example VI Parts by weight Nitrocellulose (30-40 sec. viscosity) 10 Plasticizer (Example III) Plasticizer (Example IV) 5 Milori Blue 6 Pigment (carbon black) 1-2 Solvent, in sufficient amount to make a viscous coating.

Another example is as follows:

Solvent, in suflicient amount to make a viscous coating.

For compounding the intermediate coatings b the base coating compositions, as illustrated in Examples V to VII, are thinned by adding more solvent so as to produce a more liquid coating composition. These are then applied by a roller or a brush, as illustrated in Figure 1.

A clear finish coating of a long oil varnish type is applied over the intermediate coatings b and dried overnight, or for several hours, at a temperature of from 175 to 185 degrees F. to provide a flexible gloss coat.

This final gloss coat is prepared by cooking linseed oil, perilla oil, or similar drying oil with Japanners Brown with or without the addition of metallic driers to form a flexible drying oil coating.

As an example of thiscomposition, the following is given:

Example VIII Parts by weight Linseed oil 100 Japanner's Brown (ferric hydroxide) l-Z Cobalt linoleate .01.02

In preparing the above varnish composition, the drying oil is heated to approximately 550 to 650 degrees F. for 8 to 10 hours until a heavy viscous oil is produced. When the temperature reaches approximately 450 degrees F. the Japanner's Brown and cobalt drier are added. Alter the mixture is of the desired consistency it is cooled down and thinned with petroleum naph the or other suitable solvent to produce the desired varnish consistency. The final product may be centrifuged to remove any roreign particles prior to use so as to eliminate any faulty film formation in the final coated product. Relative thin coating of the varnish is applied over the pigmented coating or enamel b. as shown in Figure 2, and is baked at 1'75 to degrees F. for 12 hours or overnight. If desired, there may be used a quick drying varnish of the alkyd resin type.

In preparing the above formulations, different pigments may be utilized to produce different color effects and it will be understood that variations in the use of driers and drying oils may be made without departing from the spirit and scope of this invention.

It will also be understood that this invention is not limited to the particular examples given and that variations may be made in the formulations by substituting equivalent materials and varying the formula over a range without departing from the scope of this invention.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A patent leather comprising a flexible base and a coating thereon, said coating comprising a nitrocellulose film forming constituent, pigment, and a plasticizer, and having applied thereover, a secondary coating of varnish or enamel, each of said coatings including a plasticizer comprising the reaction product of substantially 800 parts by weight of castor oil, substantially 50 parts by weight of maleic anhydride and substantially 26 parts by weight of diethylene glycol for a period of about 14 hours at a temperature of substantially 230 C., said reaction product being characterized by the fact that its acid number is about 9, and said coated product being characterized by the fact that it will retain its pliability and flexibility at extremely low temperatures, that the coating thereon will not soften or exude at temperatures of from 185 to 200 F. and will not crack or spew when subjected to weathering.

2. A patent leather comprising a flexible base and a coating thereon, said coating comprising a. nitrocellulose film forming constituent, pigment, and a plasticizer, and having applied thereover a secondary coating of varnish or enamel, each of said coatings including a plasticizer comprising the reaction product of substantially 800 parts by weight of castor oil, substantially 50 parts by weight of maleic anhydride and substantially 26 parts by weight of glycol for a period of approximately 14 hours at a temperature of substantially 2'30" 0., said reaction product being characterized by the fact that its acid number is about 9, and said coated product being characterized by the fact that it will retain its pliability and flexibility at extremely low temperatures, that the coating thereon will not sotten or exude at temperatures of from 185 to 200 F. and will not crack or spew when subjected to weathering.

WILLIAM D. HEDGES. JOHN C. LOWMAN. THOMAS J. KERR. 

